Growth Media Wastewater Treatment Reactor

ABSTRACT

A reactor chamber for placement in a wastewater treatment system, where the reactor chamber has a chamber formed from a sidewall which forms an interior of the chamber. The sidewall has a top portion and a bottom portion and fixed channel growth media positioned in the interior of the chamber. The fixed channel growth media is positioned below the top of the sidewall, so that when positioned in a treatment system, most of the growth media is located below the water level in the treatment system. The top of the sidewall near the water level (when positioned in a treatment system) is substantially impermeable to wastewater. The reactor includes an air distribution manifold system having a series of air release sites positioned below the fixed channel growth media and adapted to release air which disperses upwardly through the fixed channel growth media. Influent is discharged into the treatment tank near the air discharge sites.

CROSS REFERENCE

This application is a continuation of application Ser. No. 11/063,084filed on Feb. 22, 2005, which is a continuation-in-part of applicationSer. No. 10/447,464 filed May 29, 2003, and claims the benefit thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to wastewater processing reactors, and inparticular, to aerated fixed channel growth media reactors.

2. The Prior Art

Aerated wastewater treatment systems designed for small applications(less than 50,000 gallon daily capacity) generally involve an aerationtreatment chamber or zone for injecting air into the wastewater, and aclarifier chamber of zone, a quiescent zone in which particles areallowed to settle out of the system. An example of such a treatmentchamber is shown in Hansel. As can be seen, the aeration treatment zoneis generally an empty chamber having several air release sites, usuallylocated at the bottom of the chamber. An aerated treatment system treatswastewater through aerobic bacterial degradation of the waste materialspresent in wastewater or sewage. Aerobic bacterial metabolic degradationrequires dissolved oxygen and hence, the release of air into thetreatment chamber. Anoxic (oxygen free) degradation can also occur, andsuch is particularly efficient in removing undesired nitrates. In theHansel system, waters in the aerobic treatment chamber are aerated, andin the process of aeration, mixing occurs, assisting in the transfer ofoxygen into the wastewaters. Waters in the treatment chamber willeventually migrate to the clarifier zone. In the clarifier zone, nomixing occurs and the waters are calm, providing conditions to allowsuspended solids to settle out of the clarifier zone to be returned tothe treatment zone for further processing.

In the Hansel device, mixing and aeration occurs in a media free zone.The bacteria/microbes float freely in the treatment zone, having nosurfaces (other than the container/clarifier sidewalls) on which toattach. While such free floating bacteria are effective in treatingwastewaters, it is believed that more efficient treatment can beaccomplished by providing a surface for bacterial and microbe attachmentas in trickling type filtration systems, and directing the watersthrough the treatment media for treatment. Systems utilizing submergedgrowth media include that of U.S. Pat. No. 6,153,099 to Weis, et al;U.S. Pat. No. 5,156,742 to Struewing; U.S. Pat. No. 5,030,353 to Stuth;U.S. Pat. No. 5,200,081 to Stuth; U.S. Pat. No. 5,545,327 to Volland;and U.S. Pat. No. 5,308,479 to Iwai, et al, all incorporated byreference. In these systems, growth media is provided in the treatmentor reactor chamber (such as the floating media balls in Stuth or thecorrugated panels of Volland, and the cross flow media or vertical flowmedia manufactured by Brentwood Industries of Reading, Pa., also shownin U.S. Pat. No. 5,384,178 and U.S. Pat. No. 5,217,788, all incorporatedby reference). Air lift or air release channels or draft tubes (airliftpumps) are provided through the media, such as in Struewing (reference26), Iwai (reference 3P), Weis (reference 28), Stuth '754 (reference12), and Stuth '081 (reference 8). Air may also be released on anexternal side of the media, such as shown in Volland. However, in thesedevices, oxygen is not directly transferred to the growing biomass onthe growth media, but only indirectly and inefficiently through oxygenabsorbed in wastewaters (dissolved oxygen) transferred during the airlift operation.

Another device addressing clogging of media fixed film base treatment isthe device shown in U.S. Pat. No. 5,484,524 to MacLaren, et al(incorporated by reference). This device shows media disposed in a tankwith a central media free core. An aspirator or air release site ispositioned in the media free core, which induces a current in the tank,upward through the core, and then substantially downward through themedia (See FIGS. 8 and 9). This device does not provide oxygen directlythrough the media, and hence, still suffers from clogging (See U.S. Pat.No 6,105,593 to MacLaren, et al, describing a cleaning probe for the'524 device) and is not as efficient in providing oxygen directly to thegrowing biomass.

A device utilizing air dispersed through the fixed media is shown inU.S. Pat. No. 5,500,112 to McDonald. McDonald shows a series of chambersfilled with media. Air is released under essentially the entire mediabottom through a membrane covered panel at the tank bottom andconsequently, there is no established circulation path through the mediavolume—upward flowing waters and downward following waters areintermixed throughout the media volume. Additionally, the McDonalddevice is a series of tanks substantially filled with media: theMcDonald device lacks a media free treatment volume (a buffer zone ordilution zone). This lack results in the need for an excessive amount ofmedia to effect treatment, making the McDonald device inefficient anduneconomic. Additionally, the lack of a dilution or buffer zone in eachreactor chamber makes treatment inefficient. With no dilution zone,McDonald places the aeration panels on the floor of each reactor. Thereactor floor is where sludge (fully digested waste materials) normallywould be deposited by precipitation. The McDonald device forces sludgein all three reactor chambers to remain in suspension until the sludgecan be directed to a quiescent zone, the remote McDonald 4th chamber.However, access from one reactor to the next and eventually to the 4thzone, is through the fluid channels at the very top of the reactor, alsotending to keep sludge, which would normally participate, in suspensionin each reactor chamber. Consequently, in McDonald each reactor chamberwill have higher sludge concentration levels than in systems having adilution zone. With higher concentration of solution sludge, treatmentis more inefficient as the ratio of usable (digestible) waste materialsto total waste materials is suppressed.

In aerated growth media reactors, current flow in the system is inducedby air injection. The induced current within the media is generally anupward flow through the air lift tubes (or in the case of Volland, onthe side of the growth media) and downward through the fixed media. Inaerated growth media treatment systems, waters remote from the treatmentmedia must also be transported to the media surfaces for treatment, astreatment is substantially localized in the growth media. Hence,efficient mixing throughout the entire chamber is highly desirable. Theuse of air lift tubes generally induces a current in the treatmentcenter sufficient to provide the needed full system mixing, that is, tobring waters remote from the growth media to the growth media forcontact and treatment by bacterial colonies attached to the growthmedia.

Use of air lift tubes thus induces a current and provides indirectoxygen to the biomass. Air lift tubes also present scouring of thegrowth surfaces caused by rising bubbles interacting against the growthsurfaces. As the introduced air is not passing upwardly through thegrowth media, upward turbulence through the growth media is reduced.Reduced upward turbulence in the growth media increases the potentialfor bacterial growth to occlude the channels, thereby plugging orclogging the flow channels in the media. One attempt to minimizeplugging is shown by Volland. Volland uses corrugated panels placed backto back creating channels orientated at 60 degrees from the vertical.Volland thus tries to direct the bacterial slough-off down the channelsto the bottom of the media.

Growth media treatment systems as shown additionally introducewastewaters into the growth media by pumping incoming wastewaters into aportion of the system remote from the media, and allowing the inducedcurrent to transport the new influx of treatable materials to thetreatment media. This process, however, dilutes the raw incoming sewageor wastewater and extends the time for materials present in the incomingwaters to be transported to the treatment media.

Finally, all small plant treatment systems in the United States mustpass stringent regulatory requirements for effluent quality and plantperformance. Two of the plant performance characteristics that fixedgrowth media treatment plants have difficultly achieving are start-uptime and vacation time. These are time requirements during which a plantmust meet effluent standards: start-up time refers to the time a newlyinstalled plant must meet effluent standards after initial start-up;vacation time refers to the time a plant must meet effluent standardsafter re-starting from a dormant period (a vacation). The regulatoryrequirement for start-up vacation times are difficult to achieve forgrowth media surfaces as the biomass on the growth surfaces must eitherbe established (for start-up) or replenished after a period ofstarvation (during the dormant period). The biomass response time tocondition changes, when localized as on a growth media, is generallyslower than in the extended aeration system, such as the Hansel system.Consequently, a growth media treatment system will take longer tostart-up than an extended air treatment system.

OBJECTS OF THE INVENTION

It is an object of the invention to provide an aerated wastewatertreatment system with growth media where air flow is directed todisperse upwardly through the media.

It is an object of the invention to provide an aerated wastewatertreatment system with growth media with both upward and downward flowthrough the growth media.

It is an object of the invention to provide an aerated wastewatertreatment system with growth media of at least two differing flow paths.

It is an object of the invention to provide an aerated wastewatertreatment system with growth media and an integrated clarifier.

It is an object of the invention to provide an aerated wastewater systemusing growth media that provides for increased oxygen transfer whilemaintaining adequate circulation in the system.

SUMMARY OF THE INVENTION

The invention comprises a growth media reactor chamber designed forplacement in a wastewater treatment system. The growth media reactor isa side-walled chamber having a growth media positioned therein, wherethe bacterial growth media creates fixed airway passages through thegrowth media. The outer walls of the chamber extend above the growthmedia. When positioned in a treatment system, the growth media issubstantially at or below the water level in the treatment system.Generally positioned below the media is a series of air release sites,allowing air released from these sites to disperse upwardly through themedia. When positioned in a treatment center, inlet waters are directlydischarged into the top of the reactor chamber. The top portion of thewalls of the reactor chamber should fluidly isolate the top interiorportion of the reactor chamber from the top exterior portion of thereactor chamber. The reactor chamber creates a mixing/treating zonewithin the wastewater treatment system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a prospective view of one embodiment of the present inventionshowing the major components of the treatment system.

FIG. 1A is a vertical cross-sectional view through FIG. 1.

FIG. 1B is a top view of the embodiment shown in FIG. 1.

FIG. 2 is a prospective view of a prior art treatment system.

FIG. 2A 1 is a side cross-sectional view of another embodiment of theinvention.

FIG. 2A 2 is a top cross-sectional view of another embodiment of theinvention.

FIG. 2B 1 is a side cross-sectional view of another embodiment of theinvention.

FIG. 2B 2 is a top cross-sectional view of another embodiment of theinvention.

FIG. 2C 1 is a side cross-sectional view of another embodiment of theinvention.

FIG. 2C 2 is a top cross-sectional view of another embodiment of theinvention.

FIG. 3A is a side cross-section of an embodiment of the invention wherethe mixing zone is essentially the interior of the reactor.

FIG. 3B is a top elevation view of the invention depicted in

FIG. 3A.

FIG. 4 is a cross-section view through another embodiment of the reactorand air release locations, where the air release locations arepositioned internally in the reactor.

FIG. 5A is a side view (edge on) of six cross flow panels.

FIG. 5B is a prospective view of two adjacent cross flow panels showingthe orientation of the corrugations on adjacent sheets as being opposed.

FIG. 6A is a side view of two adjacent panels of vertical flow fixedchannel media.

FIG. 6B is a prospective view of two adjacent panels of vertical flowfixed channel media.

FIG. 7 shows a front elevation view of a fixed channel media panelhaving a series of dimples creating a series of fixed channel cross flowpaths.

FIG. 8A is a prospective view of a reactor having vertical cross flowfixed channels where the sidewalls are constructed from the verticalflow media panels.

FIG. 8B is a prospective view of a reactor having cross flow fixedchannels where the sidewalls are constructed from the cross flow mediapanels.

FIG. 9 is a top cross-sectional view of a reactor showing the mediasheets, where some portion of the sheets extends above the water level.

FIG. 10 shows a cross-section view of a reactor having a mixture ofvertical flow and cross flow media panels.

FIG. 11 shows a horizontal cross section of the treatment system showing(by the reference to the dashed area) possible locations of the inletterminus.

FIG. 12 shows another embodiment of vertical flow media.

FIG. 13 shows a reactor volume constructed from the panels of FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

A. The Treatment System—Retrofit

Shown in FIG. 2 is a prospective view of a prior art Hansel system,showing a tank 1, a sidewall 2 creating an internal volume consideredthe clarifier (also called the quiescent zone). The volume external tothe clarifier area contains a series of discrete air release sites 300,connected by an air distribution manifold 301 to an air compressor. Thevolume external to the clarifier area is considered the mixing zone.Wastewaters are brought into the mixing zone through an inlet 6, andremoved from the system through outlet 7 positioned in the clarifier.FIG. 1 shows a Hansel-type treatment system modified for incorporationin the present invention. Shown is tank 1, having a closed bottom andclosable top, and is generally constructed of resin reinforcedfiberglass, concrete or metal. Positioned within the tank 1 is theclarifier sidewall 2. As shown, tank 1 is a cylinder with clarifiersidewall 2 forming a second cylinder (the clarifier) having an openbottom and open top positioned in the interior of the tank 1. Located inthe interior of the clarifier is the growth media reactor 100, withgrowth media 200 positioned therein. Located below the reactor is aseries of air release sites 300, connected through a distributionmanifold 301. Inlet 6 brings incoming wastewater into the top of thereactor 100. The volume of the treatment system below the reactor 100containing the air sites 300 is considered the air release volume. Thetank's volume is thus partitioned or separated into four zones: (1) theinterior of the reactor chamber (considered the mixing zone 3); (2) theair release volume, the volume of the tank where air injection takesplace, preferentially located beneath and adjacent to the reactor; (3)the quiescent zone, the volume internal to the clarifier excluding thereactor volume; and (4) the remainder of the tank external to theclarifier, considered the dilution zone. This partition differs fromthat of the standard Hansel type system where the interior of theclarifier is considered the quiescent zone and the remainder of the tankis the mixing zone. The quiescent zone is in fluid communication withthe dilution zone through the bottom open end of the clarifier sidewall(that is, the reactor chamber does not block fluid communication throughthe clarifier bottom opening). Note, the clarifier sidewall is generallyimpermeable to wastewaters.

As shown in FIG. 1, outlet 7 removes water from the quiescent zone(here, the interior of the clarifier external of the mixing zone orreactor chamber; as shown by the dotted outline of outlet 7A in FIG. 1A,the outlet 7 may also be positioned in the dilution zone external to theclarifier). The mixing zone 3 is in fluid communication with thequiescent zone 4 through with the interior of the clarifier, and influid communication with dilution zone through the open bottom 5 of thereactor chamber and the open bottom of the clarifier. The outlet 7removes treated waters from the system. Also shown is air manifold 301connected to a source of air (a compressor, not shown), the air manifoldterminates in a series of openings, the air release locations 300,located beneath the reactor chamber 100. When the air manifold ischarged, air travels through the manifold to be discharged from the airrelease locations. A preferred structure for the air release location isshown in U.S. Pat. No. 5,714,061 to Guy, et al, incorporated herein byreference. In addition, the opening of the air release location may beterminated in an open “L” shaped pipe fitting. Upon system start-up,water in the air manifold may be discharged through the open ends of theair release locations. The L shaped fitting acts to re-direct downwardflow of wastewater emanating from the air distribution manifold awayfrom the bottom of the tank to minimize sediment disturbance. In most ofthe figures, the general locations of the air release sites areindicated by an “O.” The “O” is intended to show the general location,but not the structure, of an air release location.

FIG. 1A shows a cross-section through the treatment system in FIG. 1,while FIG. 1B shows a top view of the treatment center in FIG. 1. Anadditional feature shown in FIG. 1A is a recirculation means, here anair lift tube 700, later described.

The specific geometry of the tank arrangement utilizing a growth mediareactor can vary. Shown in FIGS. 2A-2C are other arrangements of tankand clarifier sidewalls. In FIG. 2A, a top and side cutaway view acircular tank 1 is shown with the clarifier sidewall 2 forming acylinder positioned in the tank 1. In this embodiment, the mixing zone 3is three reactors 100 located in the dilution zone located between theclarifier sidewall 2 and the exterior wall of the tank. Outlet 7 islocated in the quiescent zone internal to the clarifier. Each reactor100 has an inlet 6 (connected through a wastewater distributionmanifold, not shown) and an associated air release volume shown directlybeneath each reactor chamber. Inlet 6 empties directly into the interiorof each reactor chamber 100 and an outlet 7 draws water from thequiescent zone 4 for discharge from the treatment system. Each reactorhas growth media 200 positioned in the reactor with discrete air releaselocations 300 positioned below the reactor 100 A discrete air releaselocations.

In FIG. 2B, a top and side cross-sectional view of a rectangular tank 1is shown with clarifier sidewall 2 partitioning the tank volume into twoadjacent rectangular volumes, the clarifier volume being the quiescentzone, and the dilution zone. Located in the dilution zone portion is thereactor 100, with the interior of the reactor forming the mixing zone 3.The air release volume is positioned below the reactor. As shown, theclarifier sidewall 2 stops before reaching the bottom of the tank,allowing fluid communication across the clarifier sidewall 2 (theclarifier sidewall 2 in this embodiment is typically sloped to create azone having larger volumes near the water surface than below the watersurface). Also shown is a deflection plate 500 positioned at the bottomof the portion of the tank partition remote from the reactor 100 tore-direct solids settling out of this zone back into the area of thetank containing the reactor chamber.

Shown in FIG. 2C is a square tank 1, with a four sided sidewall 2forming a pyramidal shaped truncated open bottom frustum clarifier.Shown within the clarifier interior is a reactor chamber 100, airrelease locations 300 positioned below the media 200 located in thereactor chamber 100, and an inlet 6 (emptying into the top of thereactor chamber) and outlet 7 located in the quiescent zone interior tothe clarifier. The air distribution system is not shown in FIGS. 2A and2C for clarity. The reactor chamber is positioned above the tank bottomand can be supported from the bottom of the tank (by using a stand), orsupported from the top area or sides of the tank (or clarifier sidewall) by the use of brackets or the like.

As shown, the invention can conveniently and economically beincorporated into a variety of existing treatment systems, such as by aconverting septic (or anaerobic) system into an aerobic system throughincorporation of the growth media reactor and air injection system.Alternatively, the invention can be incorporated into a Hansel typeaerobic system, as shown in FIGS. 1A, 2A-2C. In these types of aerobicsystems, the reactor can be placed in the clarifier or external to theclarifier.

Common features of these treatment systems are inlet 6 which bringswastewater into the mixing zone (and more preferred, discharging intothe mixing zone above the water level in the mixing zone) while outlet 7removes treated waters from the treatment system external to the mixingzone, either the quiescent zone or the dilution zone. Additional commonfeatures are the placement of air release locations 300 below thereactor chamber 100 to create the air release volume. It is necessarythat air diffuse upwardly through the reactor chamber. Releasing air todiffuse upwardly through the reactor provides direct contact of oxygenwith the active biomass growing on the growth media within the reactor.Such direct contact promotes efficient (a) oxygen intake, (b) microbialmetabolism and (c) degradation of waste matter in the wastewater. Whilesome released air may also flow around the exterior of the reactorchamber (in which case there would be no quiescent zone), it is notpreferred.

When the tank is operational, the tank will have a water level 8,generally defined by the level of the outlet discharge. The reactorchamber has an outer sidewall 101 which is positioned above the waterlevel and is constructed of materials near the water level tosubstantially fluidly isolate the mixing zone 3 and the quiescent zones4 (or the dilution zone if the reactor is placed in the dilution zone)near the water level 8 in the tank. The growth media 200 positioned inthe reactor 100 is generally located below the water level 8. It isdesired that a majority of the wastewaters entering the system frominlet 6 traverse into the mixing zone for treatment, rather thanentering the dilution zone. This allows for direct contact of the highstrength waters with the biological mass in the mixing zone 3 prior todilution. For this reason, it is desired that the outer sidewall 101substantially fluidly isolate the mixing zone 3 from waters exterior themixing zone 3 near the water level 8 of the chamber. Some leakagethrough the sidewall is possible, but not preferred. However, leakagethrough the sidewall at locations distant from the inlet is moretolerable. In certain designs, substantial leakage is allowed, forinstance where the top portion of the mixing zone 3 is partitioned, aslater described.

When a growth media reactor 100 is included within a clarifier structure(as shown in the previous embodiments, FIGS. 1A, 2A-2C), it may bedesirable for the growth media reactor 100 to dispense with a separatesidewall 101 and use in its place the clarifier sidewall 2 as the outerchamber wall 101 (that is, the sidewall of the clarifier can function asthe outer wall or sidewall of the growth media reactor, for instance,where the reactor occupies much of the internal space of the clarifier).The clarifier sidewall extends above the water surface and is imperviousto wastewater (in the sense that wastewater cannot flow through thesidewall) and hence has the desired properties of a reactor sidewall.

An alternative to above mentioned treatment systems is shown in FIG. 3Aand 3B. FIG. 3 represents a “stand alone” reactor in a treatment system,not utilizing or incorporating a separate clarifier structure. In thisembodiment, the treatment tank has three recognizable volumes or zones:(1) the mixing zone interior to the reactor; (2) the air release volume,the volume generally below the reactor where air is released or injectedinto the treatment system; and (3) the remainder of the treatment tank,considered the dilution zone. As shown in FIG. 3A, the growth mediareactor 100 has an outer sidewall 101 forming a chamber having asubstantially opened top 103 and bottom 104. Also shown is recirculationmeans 700 later described.

B. The Growth Media Reactor

For the embodiment of FIG. 3A, the growth media reactor 100 has an outerwall or outer sidewall 101 which extends above the upper surface of themedia positioned within the reactor extends above the water level 8 inthe treatment system. As indicated above, the outer walls 101substantially fluidly isolate the top portion of the mixing zone 3 fromthe other surface waters in the tank, that is tank waters exterior tothe mixing zone 3 do not substantially communicate with the mixing zone3 thorough the top portion of the reactor chamber. In general, thesidewall will be impermeable to wastewaters along the entire length ofthe sidewalls. In FIG. 3A, the mixing zone 3 is in fluid communicationwith the remainder of the treatment system through the open bottom 104of the outer walls 101 of the growth media reactor 100. Inlet 6 ispositioned to release waters into the top of the growth media reactor100. Located in the interior of the growth media reactor 100 is thegrowth media 200 which provides the attachment surfaces to whichcolonies of bacteria adhere to. It is preferred that the upper surfaceof the growth media 200, positioned within in the reactor walls 101, bebelow the water level 8 to allow for distribution of incoming wastewateracross at least a portion of the top surface of the reactor.

If the growth media 200 is formed from impervious panels, the outerwalls 101 of the growth media reactor 100 may be partially or whollyformed by panels (shown in FIG. 8B). Positioned below the growth media200 in the growth media reactor 100 is the air release sites or sites300. As shown in FIGS. 3A and 3B, six air release sites 300 are providedand are distributed near the bottom portion of the reactor 100 close tothe bottom surface of the growth media 200 (again, the air distributionmanifold is not fully shown).

In all embodiments, the inlet 6 empties into the top portion of thegrowth media reactor 100 which is isolated from the adjacent surfacewaters of the quiescent zone or dilution zone by the sidewall 101 orouter wall of the mixing zone. This inlet location is desired to insurethat inlet waters, upon entering the treatment system, pass through asubstantial portion of the growth media prior to entering the dilutionzone to be diluted with the large volume of water present in thedilution zone. In this fashion, incoming high-strength (high BOD)wastewaters will be exposed to the biomass for more efficient treatmentthan would be possible with diluted (lower BOD) wastewater if the inletwere located in the dilution zone.

An additional feature shown in FIG. 3A is that the outer walls 101 ofthe reactor chamber 100 extend downwardly past the air release locations300. This aspect of the device “shields” the air release locations orthe air release volume from the dilution zone (or quiescent zone) toinsure that air released at the release locations travel through themixing zone 3 and not elsewhere. This shield or skirt portion 105 may bea separate structure attached to the growth media reactor, the airdistribution manifold or other structure, or dispensed with alltogether.

Growth media 200 is positioned slightly below the water surface 8 in thegrowth media reactor 100 (approximately 1-2 inches below the surface,although greater depths could be used). This placement of the growthmedia 200 allows the incoming wastewaters to be distributed across alarge portion of the top surface of the reactor allowing the incomingwaters access to a large portion of the reactor volume for“presentation” to the biomass in the reactor volume for treatment. Whilenot preferred, the growth media 200 may be positioned at the water level8 and mixing and distribution across the top surface will beaccomplished by upwardly flowing currents induced by air released fromthe air release locations.

Shown in FIG. 4 is another embodiment of the reaction chamber 100. Inthis embodiment, the reactor chamber has a top 110 and a bottom section130, and the air release volume 120 is located within the reactorbetween the top and bottom sections. Disposed in portions of the top andbottom sections are growth media. Located in the intermediary section120 are the air release locations or site(s) 300. It is preferred thatgrowth media 200 substantially fill the top section 110, but may notnecessarily fill the bottom section 130. The growth media 200 disposedin the top section 110 and the bottom section 130 may have differentcharacteristics.

C. The Growth Media

Growth media 200 is media that provides a surface area forbacteria/microbes to attach and grow on to develop an active, thrivingbiomass. The growth media is positioned within the growth media reactor100. It is preferred that the growth media be positioned in the growthmedia reactor below the water level in the mixing zone, as shown inFIGS. 2 and 3.

Preferred growth media is a fixed channel media consisting of a seriesof fixed corrugated panels. As used herein, “fixed channel media” isused to define a growth media that creates spatially fixed paths wherethe path is spatially invariant as opposed to a spatially variant pathas would be present when the growth media is free floating loose media,such as disclosed in U.S. Pat. No. 5,911,877 (FIG. 3) to Perez(incorporated by reference). “Fixed channel cross-flow media” means afixed channel media where a particular channel or path is in fluidcommunication at locations along a portion of the channel length with atleast one adjacent or near by channels. Non-cross flow fixed channelmedia would hence be fixed channels with substantially no fluidcommunication between adjacent or nearby channels along the channel'slength. Types of fixed channel media are disclosed in U.S. Pat. No.5,217,788 and 5,384,178, herein incorporated by reference.

One type of fixed channel media are corrugated panels positioned in avertical orientation so that the corrugations created a plurality offixed upwardly orientated channels or pathways through which air, whenreleased under the panels, travels upwardly through the channels to thesurface waters in the mixing zone. Two types of fixed channel growthmedia are preferred, that being cross flow media and vertical flow mediamanufactured by Brentwood Industries of Reading, PA. Both types of mediaare composed of a series of corrugated plastic panels as described inthe Brentwood brochures, incorporated by reference.

In the Brentwood cross flow media shown in FIG. 5A (an edge on view),each corrugated panel 1000 has corrugations 1100 placed at an angle tothe vertical (in one embodiment, the angle is about 45-60 degreesdegrees). As shown in FIG. 5B, adjacent panels 1000 are positioned in amirror image arrangement so that the corrugations on adjacent panels areorientated in the opposite direction from the adjacent panels (forinstance, if one panel has corrugations at +60 degrees from thevertical, the next panel [if the angle is kept constant] would havecorrugations orientated at −60 degrees from the vertical). Thisarrangement is accomplished by “flipping” or rotating adjacent panelsabout the vertical centerline, demonstrated in FIG. 5B.

This arrangement of adjacent sheets creates a criss-crossing pattern ofopposed corrugations on adjacent sheets. Each corrugation creates anupwardly directed fixed channel which crosses or opens into a series ofopposed corrugations formed by the adjacent panel. Each channel orcorrugation is in fluid communication with each crossing channel orcorrugation of the adjacent sheet. Hence, air released beneath adjacentsheets will take a zigzag path through the opposing sheets, eventuallyto reach the surface water. Such a zigzag path allows released air to bein contact with the growth media for a longer period of time, promotingoxygen transfer to the biomass. The zigzag pattern also promotesmixing/redistribution of the wastewater within the media.

The panels are sufficiently rough or roughened to provide an attachmentsurface for bacteria. Other types of fixed panel or fixed channeldesigns will also provide upwardly directed channels with crisscrossingpaths. For instance, panels constructed with discrete indentations ordimples 60 orientated along an angle, as shown in FIG. 7, will alsoprovide a zigzag path with fluid communication across the entire widthof adjacent panels. It may also be desirable to have fluid communicationbetween adjacent panels, such as by providing cutouts in the panels.

Another type of fixed channel media is the Brentwood vertical flowpanels shown in FIG. 6 and FIG. 12. The panels in FIG. 6 havesubstantially vertically orientated corrugations half way up the panel(the bottom), with the second half of the panel being substantiallyplanar without corrugations (the top). Adjacent panels are placed withthe top of one placed adjacent the bottom of the adjacent panel, asindicated in FIG. 6B. The panels in FIG. 12 depict a second panel whichcreates vertically orientated flow paths when combined with additionalpanels, as shown in FIG. 13. Vertical flow panels can also be formedfrom discretely formed channels (such as tubes) and stacked together tocreate a honeycomb of vertical channels. The corrugations can be at anangle from the vertical, or substantially vertically formed, as shown inFIG. 6B and FIG. 12. Vertical flow channel media allows the upwardtravel of air released below the media to proceed with few changes ofdirection, that is, with few zigzag paths available. Obviously, if thevertical paths are orientated on an angle, the upward path of air willbe angular, but generally not a zigzag path as would occur in cross flowmedia. As used herein, “vertical flow fixed channel media” is used todefine a growth media that creates spatially fixed channelssubstantially vertically orientated. Such media may have some sharpchannel path directional changes, such as embodied by the BrentwoodIndustries vertical flow media.

When fixed channel media is employed, the outer walls 101 of the growthmedia reactor 100 may be formed from the panels of the fixed channelgrowth media. For instance, if using a cube formed from a series of thecross flow media panels, the two terminal side panels 108 will form twoouter opposing walls (non-porous along the length). The remaining twoside walls of the reactor can be formed from two panels 107, verticallyorientated, but orientated at 90 degrees for the remaining panel media,as shown in FIG. 8B. In this case, it is preferred that the four panelscomposing the outer side walls (107 and 108) of the reactor extendvertically above the horizontal level of the remaining panels to fluidlyisolate the interior of the growth media reactor near the water levelfrom the exterior volume adjacent to top of the growth media reactor.Because this is fairly cumbersome to construct, the growth media may beplaced in a separate open top and bottom plastic or fiberglass chamber.

Shown in FIG. 9 is a top view of a growth media reactor 100 having aseries of parallel sheets 200 as growth media. As shown, portions 500 ofthe sheets in the reactor 100 extend above the water level (thoseportions shown in solid lines are located above the water level, whilethe dotted lines represent those portions below the water line),creating a partitioning of the surface waters in the media reactor. Bysuitable placement of some portions of the sheeted growth media abovethe water level, a designer can direct the surface flows through thegrowth media reactor in a desired pattern. For instance, a partitioncould be employed to divide the top of the mixing zone into two halvesthat are substantially fluidly isolated from each other. In thisinstance, one half would receive influent from inlet 6 and the otherhalf would not. The half that did not receive influent directly from theinlet 6 would not need to be fluidly isolated from the dilution zonenear the surface waters.

Other types of growth media can be used. For instance, instead ofcorrugated sheets of solid plastic, fiberglass sheets can be used orother type of fixed film media. Corrugated sheets formed from a porousor semi-porous material could also be utilized, such as semi-porousstiff foam. Such semi-porous sheets provide for some degree of fluidcommunication through the sheet and also provide additional locationsfor bacteria to attach and grow.

As shown in FIG. 2A, air release locations 300 are positioned below thegrowth media to allow released air to travel up and disperse through thegrowth media. Several air release locations 300 are shown. The releasedair creates a circulation pattern within the growth media reactor 100:released air is entrained in rising waters to create an upward flowthrough the growth media reactor. When the upward flowing waters reachthe surface of the growth media reactor, the waters must flow downwardback through the growth media reactor as the top volume portion of thegrowth media reactor is fluidly isolated from the other surface watersin the treatment system. Waters exit the reactor from the bottom volumeof the reactor (either through the open bottom of the reactor, orthrough downward flow paths which open on the sides of the reactor).Portions of the downward flowing waters, upon exiting the growth media,will be re-directed upward by the induced upward current created by thereleased air to pass again through the growth media reactor for furthertreatment. The remaining portions of the downward flowing waters willenter the dilution zone. A circulation pattern is thus establishedwithin the reactor, and indeed, the current induced by the air injectionwill induce an overall circulation pattern in the treatment system. Thecurrent induced within the treatment system will eventually bring watersremote from the mixing chamber (that is, within the dilution zone andthe quiescent zone, if present) back to the reactor for furthertreatment. How quickly remote waters are returned to the reactor dependon the strength of the induced current. The strength of the inducedcurrent will depend on the ability of the released air and entrainedwaters to flow through the reactor chamber. In general, the morecircuitous the route through the reactor chamber, the weaker the inducedcurrent (for a given air injection rate). Additionally, if the channelsin the fixed channel media are small or the released air not flowing ata sufficient rate, a weak current will be induced. If the inducedcurrent is too weak, insufficient mixing throughout the entirewastewater treatment system may occur. That is, the induced current maybe too weak to timely bring waters in the treatment system remote fromthe reactor to the reactor for treatment. In this instance, arecirculation means may be employed.

A recirculation means recirculates waters from the dilution zone backinto the treatment chamber. One recirculation means is shown in FIG. 3.In this embodiment, the recirculation means 700 includes a tube or pipewith open ends, one end (the suction end 602) being placed in thedilution zone, and the other end 603 will empty into the top of thereactor. As shown, the discharge end 603 is shown placed above the waterlevel in the top of the reactor. The discharge end could also be placedbelow the water level in the reactor. If the treatment system includes aclarifier, it is preferred that the suction end of the recirculationmeans be positioned in dilution zone, not the quiescent zone. Locationof the suction end 602 is not critical, but it should not be too closeto the bottom (to avoid sucking in bottom sludge) and it is desirablethat the suction end be remote from the outlet or discharge 7. It isdesired that the water volume near the outlet be calm (to allowsuspended solids to settle out prior of the waters prior to discharge),and hence, the suction end should be remote from the outlet 7. Thesuction end 602 can be placed adjacent to the bottom of the reactorchamber but removed from the air injection volume.

Alternatively, to create supplemental flow through the reactor, anexisting air release location located underneath the reactor could beused. In this instance, a vertical flow channel (a 2 inch cross sectionpipe, for instance) would be placed through the reactor and locatedabove the selected air release site. Such an arrangement is shown asreference 800 in FIG. 2A.

Air from the compressor or other source is injected into the air lifttube 601 near the suction end 602. Air can be drawn from the airdistribution manifold, such as by a flexible hose or fixed tubing, forthis purpose. The injected air will rise up with entrained water toempty into the top of the rector chamber creating an addition flow ofwaters into the top of the reactor. Because the suction end 602 islocated in the dilution zone, it is desired that substantially all airinjected into the air lift tube 601 remains within the tube and does notescape into the quiescent zone.

If supplemental recirculation is needed, use of the air lift pump as arecirculation means is convenient and efficient as the present treatmentsystem uses air for injection into the system under the reactor mediaand the air distribution manifold can be tapped for delivering air intothe recirculation pipe. Obviously, other types of pumps could be used todrive a recirculation means, such as a centrifugal pump. Using arecirculation means, a supplemental current is created in the dilutionzone to help cycle waters in this zone back through the reactor chamberfor further treatment.

The induced current also induces a circulation pattern in the mixingzone, that is, within the interior of the reactor: upward flow along afirst portion of the growth media reactor and downward flow in a secondportion of the growth media reactor. This pattern may not be stable, butvary over a period of time. However, by suitable choice of airdropplacement and/or selection of types of fixed media channels, the reactorunit can be designed to produce a fairly stationary current patternwithin the reactor volume: a portion of the reactor designed for upwardflow, and a portion designed for downward flow.

It may be desirable to vary the characteristics of the growth media inthe growth media reactor 100 to take advantage of the circulationpattern within the reactor. For instance, a mixture of both vertical andcross flow fixed channel media in the reactor chamber can be utilized,with cross flow fixed channel media 525 positioned below and adjacent tothe air release locations, and with vertical flow fixed channel media550 positioned elsewhere in the growth media reactor, one suchembodiment is shown in the top view of the reactor shown in FIG. 10. Inthis embodiment, air injection occurs below cross flow media 525 andhence upward flows of waters will occur substantially in the cross flowmedia 525. Downward flow occurs in the center of the reactor through thevertical flow media 550. The velocity of the upward flow is determinedby the rate of air injection, the number of injector locations, and thetype and volume of the media employed. The down flow rate is dependentupon the type and volume of media employed for down flow in relationshipto the volume of upward flow (obviously the upward flow must equal thedownward flow). For instance, by enlarging the middle volume of thereactor chamber in FIG. 10, the down flow rate through the center can beslowed.

Using two different media characteristics for the two flow paths allowsthe designer to tailor the reactor's growth surfaces for differentproperties of the upward flowing and downward flowing waters. Watersflow upward with entrained air providing increased mixing and oxygentransfer and some scouring of the growth media walls by the rising airbubbles. Waters descending through the reactor lack entrained airbubbles, and hence, less scouring of the walls will occur on theportions of the growth reactor accommodating downward flow. With lessscouring and/or possible decreased downward flow velocity, the minimumcross sectional area of the downward flowing channels can be increased(with respect to the media accommodating upward flow) to accommodateheavier build up of bacterial growth, or build up of an alternate typeof bacterial growth.

A pretreatment tank can be placed in series with the current wastewatertreatment system, with waters from the pretreatment tank delivered tothe mixing zone. Additionally, a post-treatment tank can also beutilized in series with the output of the present wastewater treatmentsystem, with waters from the quiescent or dilution zone being the inputto the post treatment tank, such as discussed in Cormier, U.S. Pat. No.6,093,316, incorporated herein by reference.

D. Operation

While the fixed media growth reactor is highly efficient due to the highconcentration of treating biomass (it is estimated that a single passthrough the system may remove as much as 70% of the wastes), treatmentrequires a cycling of waters through the reactor. In most applications,the present treatment system operates in cycles: incoming wastes do notenter the system in a continuous flow, but enter the system in pulses ordoses. For instance, in home systems, the system will be pulsed duringthe mornings and the evenings when bathrooms are heavily utilized.During the day, the treatment system may not be pulsed at all, or pulsedinfrequently. Alternatively, input to the treatment system may beaccomplished from a pretreatment dosing tank, wherein a dosing pumpoperates to pump waters to the treatment system when the waters in thedosing tank exceed a given level.

When the system is being pulsed, incoming wastes will be directly fed tothe reactor for efficient treatment. When not being pulsed (that is, thesystem is dormant), it is desirable to continue treating the fluids inthe treatment system, that is, treat the waters in the mixing zone andthe dilution zone. In these dormant periods the treatment systemcontinues to operate to treat the water in the system by drawing wastesto the reactor for treatment by cycling waters through the reactorthough injection of air at the air release sites (generally, air iscontinuously injected into the system, unless trying to induce a periodof low oxygen levels to achieve denitrification).

The dilution zone should be sufficient to buffer the waste strength ofincoming wastewaters, and the size needed will depend upon the effluentstandards to be achieved. In large treatment systems (over 100,000gal/day) with current EPA secondary guideline effluent standards(BOD=30mg/liter TSS=30mg/liter), it is believed that the ratio ofreactor volume to tank volume should generally be under 0.50 as theinfluent approximates a continuous flow (however, this has not beentested). Further, in large scale municipal type treatment facilities,even with sufficient dilution zone capacity, it is believed that thevolume of media required to effectively achieve EPA secondary guidelineeffluent standards becomes less cost effective than other technologies.

As new influent enters the treatment system on the top surface of thereactor, the new influent must thus pass through the reactor and comeinto contact with the active biomass (at least once on the downwardflow). This is substantially different from treatment systems whereinfluent enters the system elsewhere in the treating system, as entryelsewhere implies that the influent is mixed with other wastewater andeffectively diluted prior to treatment. The diluted wastewaters now takelonger to treat. For instance, if incoming wastewaters are diluted by afactor of 10 before entering the treatment reactor, then it will take 10times longer to treat the same amount of wastes, as now ten times thewastewater must pass through the reactor to present the same wastes tothe biomass (this is somewhat simplistic, as it assumes completemixing).

The present system relies upon direct contact and dilution to meettreatment standards. The dilution zone acts to absorb and dilute wastesafter new influent passes at least once through the reactor, allowingthe overall system (reactor and dilution zone/quiescent zone waters) tomeet wastewater effluent standards. For instance, assume 300 BODwastewaters are influent, a 70% efficiency for the reactor, and dilutionin the larger dilution zone by a factor of 10. Also assume effluentstandard is 25 BOD (Biological Oxygen Demand —a measure of wastestrength, other standards also come into play, such as Total SuspendedSolids (TSS), nitrate levels, fecal coliform levels, etc). If 300 BODwaters were positioned in the dilution zone prior to entering thereactor, the dilutive effect results in an average BOD of 30 (factor often dilutions). Contrast these levels with that of the present system,where the 300 BOD waters passes through the bioreactor once and theresulting BOD, after a single pass of the influent through the reactor,would be reduced to 90 BOD (70% efficiency (the higher reactorefficiency is attributable to aeration under the reactor and the abilitypresent high BOD wastes to the biomass without dilution effects)). Afterdilution of this preliminary treated water, the strength of the watersin the treatment tank is now 9 (factor of ten dilutions). Hence, in thisinstance, the treatment system increased performance by a factor of 3,making effluent standards more readily achievable.

In period of low flows (or the system at rest), the system cycles watersthrough the reactor to remove wastes, dropping the waste levels in thewastewater and preparing the system for the next pulse of high strengthwastewaters. In period of influent, the high strength incoming influentshocks the system by raising overall BOD levels, but the high BOD watersare treated initially in the reactor and the remaining wastes arediluted in the quiescent zone allowing the system to absorb the shockand to maintain effluent standards. If the system had no periods of rest(low or no influent), wastewater BOD levels (and other pertinentperformance characteristics) would slowly rise in the tank despiteefficient treatment by the bioreactor, as the system can not “keep up”or process the continuous influent quickly enough. At some point, thesystem would fail to meet effluent standards.During the rest periods,the treatment system “recovers” from a prior period of influent bycontinuing to treat the diluted wastewater reducing further the BODlevels without having to treat new influent. Obviously, a largerdilution zone (larger volume) allows the system to adapt to longerinfluent flows or higher strength influent flows and still maintaineffluent standards. Hence, in systems where flow approximates acontinuous flow, additional treatment is desirable (more reactor volume)and additional dilution zone is also desirable.

As described, the reactor could be utilized with no clarifier structureor an internal clarifier. One embodiment structured as in FIG. 3 used a700 gallon tank (system capacity of treating about 500-700 gallons/dayof typical domestic strength wastewater (180-300 BOD, and TSS) with a2′×2′×4′ block of fixed channel media (placed in a 2′×3′×4′ chamber toisolate the top of the media from the quiescent zone), utilizing six airrelease locations (release was effected through ¾ PVC tubing) connectedto a compressor running at six c.f.m. Good quality effluent was obtainedover an extended period. More recently, higher flow rates have beenutilized (15-20 c.f.m). Higher flow rates induce more active mixing andmore efficient oxygen transfer, however, too high a flow rate willresult in scouring of the bacterial mass from the growth media. Flow wasinduced by air injectors located about two inches below the bottom ofthe reactor, and the reactor was positioned about 19 inches from thebottom of the tank floor. The system was also run using a singlesupplemental air lift pump for recirculation, producing a supplementalflow of 10 gallons/minute into the top of reactor (tapping the existingair manifold and using a 2 inch pipe as the airlift tube). Using thesupplemental air lift pump, it was found that the treatment center morereadily meet requirements for start-up and vacation. For a 2′×2′×4′reactor, tank sizes in the 200-2100 gallons range should produce areasonable treatment effluent quality; and in general, for a givenreactor volume, the ratio of reactor volume to total volume in the rangeof about 0.05 to about 0.6 (and potentially to 0.75) should produce areasonable treatment effluent quality.

For larger applications (one using multiple 2′×2′×4′ reactor unitblocks), it may be desirable to split the inlet 6 into several feedpipes to more evenly distribute the incoming wastes across the topsurface of the mixing zone. The placement of the reactor in the tankvolume is not critical, however, it is desirable that the air injectorsnot be place too close to the tank bottom, particularly for flatbottomed tanks. The tank bottom serves as sludge storage area for thetreatment system. If air injection takes place near the tank bottom, thebottom of the tank will be subject to currents and little space will beavailable for sludge storage (requiring a quiescent zone fordeposition), as the sludge will tend to remain suspended, and therebyraising the TSS levels of the effluent. It is believed that for flatbottomed tanks, the injectors should be at least 6 inches off thebottom, with 12-20 inches more preferred.

As can be seen, feeding the reactor from the top of the reactor chamberforces the wastewater to pass through the reactor, allowing for thewastes to be directly contacted with the biological mass prior tosignificant dilution. However, it is also possible to achieve similarcontact by “feeding” the reactor near the air injectors. The airinjectors create an “updraft” or upwelling current, and hence, byfeeding influent into the tank near the air injectors, the updraft willdraw the incoming wastewaters from the influent pipe and direct aportion of such waters into the reactor chamber. Possible locations forthe influent terminus include locations in the dilution zone to the sideof the air injectors or below the air injectors. Alternatively, theinfluent terminus could be located above the air injectors but below thereactor chamber. Finally, while not preferred, the influent terminuscould be positioned in the interior of the reactor chamber. For theinfluent discharging into the dilution zone, it is preferred that theinfluent terminus or discharge end location be positioned so that asubstantial amount (over 50%) of the incoming influent will be drawninto the mixing zone by action of the air injectors. FIG. 11 shows avolume near the air injectors (shown by the dashed line) for thelocation of an inlet terminus or discharge site(s) for a “bottom fed”reactor. Note that the possible volume is skewed near the side of thereactor closest to the discharge or outlet location. This is to minimizethe potential of a short-circuit, that is, influent entering the systemand reaching the outlet prior to passage through the mixing zone.Finally, if the reactor is bottom fed, is it not necessary that the topof the reactor remain substantially fluid isolated from the remainingsurface waters, however, such an arrangement is preferred.

Other uses and embodiments of the invention will occur to those skilledin the art, and are intended to be included within the scope and spiritof the following claims.

1. A treatment system comprising: (a) a tank for processing wastewater,said tank having a water level; (b) a growth media reactor positioned insaid tank, said growth media reactor having a least one outer sidewalldefining an interior forming a mixing zone, said at least one outersidewall extending above said water level, said outer sidewall adaptedto substantially fluidly isolate said interior of said reactor from theexterior of said reactor near said water level; (c) growth mediapositioned in said interior of said growth media reactor; (d) an outletremoving waters from said treatment system, said outlet exterior to saidgrowth media reactor; (e) at least one air discharge site adapted to beconnected to an air source, said air discharge site positioned so thatair released from said air discharge site will substantially flow anddisperse upwardly through said growth media; and (f) an inlet feedingwastewaters external to said tank for treatment in said treatmentsystem, said inlet discharging into said tank near said air dischargesite.
 2. A treatment system according to claim 1 wherein said growthmedia comprises fixed channel growth media.
 3. A treatment systemaccording to claim 2 wherein said at least one sidewall is partiallyformed by a portion of said fixed channel growth media.
 4. A treatmentsystem according to claim 3 wherein said side wall is substantiallyimpermeable to wastewater.
 5. A treatment system according to claim 2wherein said fixed channel growth media comprises a first componentmedia and a second component media, said mixing zone having a wastewatercirculation path having an upward flow portion and a downward flowportion, said upward flow portion substantially flowing through saidfirst component media, said downward flow substantially flowing throughsaid second component media.
 6. A treatment system according to claim 5wherein said first component media and said second component media eachform channels having a respective minimum cross-sectional area, saidminimum cross-sectional area of said first component media being smallerthan said cross-sectional area of said second component media.
 7. Atreatment system according to claim 2 wherein said fixed channel growthmedia has a first component having cross flow channels.
 8. A treatmentsystem according to claim 7 wherein said fixed channel media has asecond component substantially lacking cross flow channels.
 9. Atreatment system according to claim 2 wherein said fixed channel growthmedia is composed of a series of vertically orientated panels formingchannels between adjacent panels.
 10. A treatment system according toclaim 7 wherein said cross flow channels are orientated at an angle fromthe vertical.
 11. A treatment system comprising: (a) a tank forprocessing wastewater, said tank having a water level; (b) a clarifierpositioned in said tank defining a quiescent zone; (c) a growth mediareactor positioned in said clarifier, said growth media reactor having aleast one outer sidewall defining an interior forming a mixing zone,said at least one outer sidewall extending above said water level, saidouter sidewall adapted to substantially fluidly isolate, in a regionadjacent to said water level, said mixing zone from the exterior of saidmixing zone; (d) growth media positioned in said interior of said growthmedia reactor; (e) an outlet removing waters from said mixing zone, (f)at least one air discharge site adapted to be connected to an airsource, said air discharge site positioned so that air released fromsaid air discharge site will substantially flow and disperse upwardlythrough said growth media (g) an inlet feeding wastewaters external tosaid tank for treatment in said treatment system, said inlet dischargingnear said air discharge site.
 12. A treatment system comprising: (a) atank for processing wastewater, said tank having a mixing zone and adilution zone separated by at least one sidewall positioned in saidtank; said mixing zone having a bottom portion in fluid communicationwith said dilution zone; (b) said dilution zone and said mixing zonehaving a water level; (c) an outlet positioned in said dilution zone,said outlet located at or below said water level in said dilution zone;(d) growth media positioned in said mixing zone, said growth mediapositioned substantially below said water level; (e) an air dischargesite adapted to be connected to an air source, said air discharge sitelocated near said lower portion of said growth media and positioned sothat air released from said air release site will substantially flowupward diffusing only through said mixing zone; and (f) an inletpositioned in said tank to discharge into said near said air dischargesite.
 13. The treatment system of claim 1 wherein said inlet ispositioned below said air discharge site.
 14. A treatment systemcomprising: (a) a tank for processing wastewater, said tank having awater level; (b) a growth media reactor positioned in said tank, saidgrowth media reactor having a least one outer sidewall defining aninterior forming a mixing zone, said at least one outer sidewallextending above said water level; (c) growth media positioned in saidinterior of said growth media reactor; (d) an outlet removing watersfrom said treatment system, said outlet exterior to said growth mediareactor; (e) at least one air discharge site adapted to be connected toan air source, said air discharge site positioned so that air releasedfrom said air discharge site will substantially flow and disperseupwardly through said growth media; and (f) an inlet feeding wastewatersexternal to said tank for treatment in said treatment system, said inletdischarging into said tank near said air discharge site.
 15. A method oftreating wastewaters in a treatment tank, said wastewater having a waterlevel in said treatment tank, said treatment tank including growth mediapositioned in said tank and at least one air discharge site, an inletand an outlet, said method including the steps releasing wastewatersfrom said inlet into said treatment tank below said water level in saidtreatment tank and near said air discharge site, aerating wastewatersnear said growth media so that air released from said air discharge sitewill substantially flow and disperse upwardly through said growth media;and removing wastewaters from said treatment tank through said outlet.